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Systems · 16 pages
Systems

System designs — overview

How real products are actually built — block-level walkthroughs of seven everyday embedded systems, from Wi-Fi routers to flight controllers.

1 min read · 240 wordsupdated · May 12, 2026

The rest of armhub treats topics one at a time: a peripheral, a core, an RTOS. This section flips that orientation — we pick a finished product and walk it backwards into the silicon and firmware that make it work.

The goal is grounded. When you read about Cortex-A53, you can come here to see one of the millions of devices it actually ships in. When you read about hard real-time, you can see why a drone flight controller picks one core architecture over another.

What each page covers

  • At-a-glance specs — chip class, RAM/flash, OS, peripherals, certifications.
  • Block diagram — the silicon you'd see if you decap'd the SoC.
  • What the cores do — every CPU/coprocessor and what it owns.
  • Software stack — bootloader, OS/RTOS, key middleware.
  • The hard parts — failure modes, certifications, non-obvious tradeoffs.
  • Real products — concrete examples you can buy and tear down.

The seven devices

Wi-Fi router (Wi-Fi 6 consumer)

MediaTek MT7986 / Qualcomm IPQ8074 class. Quad Cortex-A53 + dedicated Wi-Fi MAC/PHY. Linux/OpenWrt. ~$80–$250 retail.

Smartwatch / fitness tracker

Cortex-M33 + BLE radio (Nordic nRF53/54 class). 5–15 day battery, sensor fusion, GATT services, AMOLED touchscreen.

Drone flight controller

Cortex-M7/M85 (STM32H7, RA8). 8 kHz control loop, IMU + barometer + GPS, PWM/DSHOT to ESCs. Pixhawk/PX4 stack.

EV charger (Level 2 home)

Cortex-M7 + WiFi MCU. PWM control-pilot signal, residual-current protection, OCPP 1.6/2.0 over WiFi, 7.2–11.5 kW.

Smart thermostat

Cortex-M33 + Wi-Fi/Thread radio (nRF7002, EFR32MG24). Capacitive touch, e-paper/LCD, HVAC relays, Matter.

Automotive ECU

ASIL

Cortex-R52 lockstep + Cortex-M for I/O. CAN-FD, ISO 26262 ASIL-B/D, AUTOSAR Classic, hard real-time.

Industrial motor drive

Cortex-M4F (STM32G4) or M7. Advanced PWM timer, current-sense ADC sync'd to inverter, FOC at 16–32 kHz, CANopen/EtherCAT.

How to read these

Each page assumes you've read the relevant background pages — but you can absolutely jump straight in. Cross-references are everywhere, and you'll often find that one device touches half the rest of the site: a Wi-Fi router uses Cortex-A, Linux boot flow, DMA, USB, and vendor SoCs.

A flight controller touches Cortex-M7, SPI, I²C, DMA cache coherency, Rust on Cortex-M, FreeRTOS, and linker scripts for ITCM placement.

That's the point of this section — to make the rest of the site useful in context.